Method of making vented test barrel assembly for revolver ammunition

ABSTRACT

A test barrel assembly for a universal receiver includes a cylinder, having a cartridge-receiving chamber, and a barrel secured to the cylinder in a manner such that a rifled bore of the barrel is in axial alignment with the chamber. Spacer means between the cylinder and barrel provides a gap of predetermined thickness therebetween and the resulting controlled venting of propellant gases through the gap during firing results in reproducible pressure and velocity readings which can be used to accurately predict actual performance of a cartridge in a revolver. Manufacture of the cylinder and barrel from a single piece of steel ensures proper alignment and uniform spacing of these parts.

United States Patent Bateman, Jr. et a1.

Trumbull; James J. Capasso, Shelton, all of Conn.

Remington Arms Company, Inc., Bridgeport, Conn.

Filed: July 10, 1974 Appl. No.1 487,055

Related U.S. Application Data Division of Ser. No. 347,381, April 3, 1973, Pat. No. 3,854,331.

[73] Assignee:

U.S. c1. 29/416; 29/412; 29/414; 29/464; 29/558 1m. c1 B23p 17/00 Field Of Search 29/412, 558,414, 416, 29/428, 464; 73/167, 35

References Cited UNITED STATES PATENTS 12/1939 Fykse 29/416 2/1960 Aspelin 29/428 X Primary ExaminerC. W. Lanham Assistant Examiner-Victor A. DiPalma Attorney, Agent, or Firm-John H. Lewis, Jr.; Nicholas Skovran; William L. Ericson [57] ABSTRACT A test barrel assembly for a universal receiver includes a cylinder, having a cartridge-receiving chamber, and a barrel secured to the cylinder in a manner such that a rifled bore of the barrel is in. axial alignment with the chamber. Spacer means between the cylinder and barrel provides a gap of predetermined thickness therebetween and the resulting controlled venting of propellant gases through the gap during firing results in reproducible pressure and velocity readings which can be used to accurately predict actual performance of a cartridge in a revolver. Manufacture of the cylinder and barrel from a single piece of steel ensures proper alignment and uniform spacing of these parts.

5 Claims, 5 Drawing Figures PATENTED MAY 2 7 I975 SHEET OZUF 2 METHOD OF MAKING VENTED TEST BARREL 7 ASSEMBLY FOR REVOLVER AMMUNITION This is a division of application Ser. No. 347,381, filed Apr. 3, 1973, now US. Pat. No. 3,854,331.

This invention relates to ballistic measurement and more particularly to a test barrel assembly for accurately and reproducibly measuring chamber pressure and muzzle velocity for revolver cartridges.

In the manufacture of ammunition, it is important that interior ballistic data for each type of cartridge be known. Accurate measurements of both chamber pressure and muzzle velocity must be made to determine whether the cartridge will fire safely and, additionally, how it will perform in a gun. These readings must account for all variables affecting interior ballistics, including the caliber and type of cartridge and bullet, the type and quantity of propellant powder, and the type of primer as well as operating characteristics of the gun, such as the type of gun and the length of its barrel.

It has been determined that these measurements can be most effectively made by utilizing a universal receiver. This is a mechanism of great structural strength which is securely mounted and simulates firing in an actual gun. Certain portions of the universal receiver are useable with all calibers and types of ammunition, such as the breech block, firing pin, and a firing mechanism capable of remote operation. To accommodate different cartridge types and sizes, a large number of different barrel assemblies, each having its own chamber, may be selectively attached so that the same receiver can be used to test fire virtually any type of small arms ammunition. The replaceable barrel assembly is adapted to permit the measurement of chamber pressure by compression of a metal slug or by use of a transducer, each method being well known to those skilled in the art.

The universal receiver makes it possible to obtain reproducible pressure and velocity readings and permits variables,.such as barrel length, to be controlled. Thus, its use is much preferable to the alternative of obtaining these values from actual firearms, inasmuch as additional variables relating to the interaction of parts or defects in the gun may be introduced, thus rendering the pressure and velocity data obtained of little value or validity for any gun other than the one on which they were measured.

While the universal receiver, fitted with an appropriate barrel assembly, has been able to provide appropriate ballistic data for rifles, shotguns and most hand guns, the results obtained for revolver ammunition has been virtually meaningless. Barrel assemblies available in the prior art have been unable to simulate actual firing conditions, because in a revolver, the relationship between the revolving cylinder and the barrel results in a significant venting of propellant gases not heretofore reproducible by a test barrel assembly.

The use of actual revolvers for ballistic testing did not alleviate this problem because design differences in different revolvers result in significant variations in the amount of gas which is vented and because the erosion of parts on a revolver with repeated use causes the amount of gas vented by each revolver to increase significantly during the life of the gun. For these reasons, it has been heretofore impossible to provide reproducible ballistic data which would apprise a revolver owner of the pressure and velocity information required for an accurate determination of how his revolver would perform when loaded with a particular type of ammunition. Additionally, information regarding bullet mushrooming and accuracy obtained through the use of prior art test barrels has been incorrect when applied to revolvers.

In accordance with this invention, a test barrel assembly for a universal receiver has a cylinder and a barrel which are attached together with a cartridgereceiving chamber in the cylinder in axial alignment with a rifled bore of the barrel. A plurality of spacers of predetermined length are utilized between the cylinder and barrel so that a gap of predetermined thickness is provided between the cylinder and barrel. In this manner, the firing conditions of a revolver can be satisfactorily duplicated and reproducible pressure and velocity data may be obtained which accurately predicts the performance of a particular type of ammunition in a revolver in good condition. [By substituting spacers of greater length, the gap may be increased permitting measurement of the deterioration in the interior ballistics of a revolver, resulting from wear caused by extended use, so that performance under these conditions can also be predicted.

The cylinder and barrel are manufactured from a single piece of metal in which passages which require accurate alignment, such as the chamber and bore, are drilled prior to separation of the cylinder from the barrel. After separation, the cylinder and barrel are mounted on a mandrel which fits the exact bore dimension so that proper alignment may be maintained during assembly.

It is an object of this invention to provide a test barrel assembly for testing revolver ammunition in a universal receiver.

It is another object of this invention to provide a test barrel assembly for testing revolver ammunition in a universal receiver which reproduces the firing conditions in a revolver.

It is an additional object of this invention to provide a test barrel assembly for testing revolver ammunition in a universal receiver in which the thickness of a gap between the cylinder and the barrel is adjustable so that the conditions of both new and worn revolvers can be simulated for the accurate and reproducible measurement of corresponding internal ballistic data.

These and other objects and advantages of this invention will be more apparent when the following specification is read in conjunction with the appended drawings, wherein:

FIG. 1 is a side elevation, partially cut away, of a universal receiver housing a test barrel assembly made in accordance with this invention;

FIG. 2 is a breech end view of the test barrel assembly of this invention;

FIG. 3 is a cross-sectional view of the test barrel assembly taken generally along the line 3--3 of FIG. 2;

FIG. 4 is an exploded perspective view of the test bar rel assembly of FIGS. 2 and 3; and

FIG. 5 is a side elevation of a machined blank used in making the test barrel assembly of this invention.

Referring now to the drawings, FIG. 1 illustrates a universal receiver 11, generally comprising a body member 12 which is adapted to be fixed to a support by a bolt extending through an opening 14, encloses a breech member 15 at one end, and has at its other end a lock nut 16 for clamping to it a suitable test barrel assembly 17. The breech member is operated by a handle 19. A firing pin is mounted in the receiver and adapted to be struck by a hammer (not shown) which is, in turn, operated by a trigger mechanism including a lever 21 pivoted on a shaft 22 and a lever 24 pivoted on a pin 25 in a slot intermediate the ends of the lever 21. The lever 24 has at one end an extension arranged to engage the hammer. The firing pin 20 is operated by moving the lever 21 rearwardly. This biases the hammer away from the firing pin and then releases the hammer so that it impacts the firing pin and fires the cartridge in a manner well known to those skilled in the art.

Mounted on the top of the body member 12 in an open space between a pair of wall portions 12a of the body member is a device 26 for registering the pressure developed within the barrel.

Referring now to FIGS. 1-4, the test barrel assembly 17 generally consists of a cylinder 27 and a barrel 29, both preferably machined from the same piece of steel. The cylinder 27 has a breech end portion 27a of reduced diameter and has an axial passage bored therethrough and having a proper contour and dimensions to serve as a chamber 30 for containing a cartridge to be tested. A radial passage 31 communicating with the chamber 30 may be provided to accommodate the measurement of chamber pressure and may contain a piston 32 so that pressure may be measured by determining the amount by which a metal slug of predetermined length held by the pressure measuring device 26 is compressed by the pressure exerted by propellant gases, in a manner well known to those skilled in the art. Alternatively, the passage 31 may contain a transducer which, when coupled with appropriate electronic readout equipment, produces a direct measurement of chamber pressure. A plurality of blind bores 34 are preferably drilled and tapped around the chamber to accommodate attachment of the cylinder to the barrel. In the preferred embodiment, the cylinder 27 has a forward extension 27b of reduced diameter formed integrally therewith. This forward extension 27b may be on the order of 0.125 in. in length. An alignment notch 35 may be formed in the breech end of the cylinder 27 for interaction with an alignment stud 36 in the universal receiver 11 to ensure the proper orientation of the test barrel assembly 17.

The barrel 29 may be of any desired length but is preferably about 2, 4 or 6 in. in length to simulate actual revolver barrels. The barrel 29 has an enlarged attachment portion 29a at a rear end thereof. An axial passage is provided through the barrel and preferably rifled to serve as a bore 37. A plurality of passages 39 are preferably provided in the attachment portion 29a of the barrel 29 in alignment with the corresponding blind bores 34 in the cylinder 27 so that threaded attachment means, such as a plurality of cap screws 40, may be used to secure the barrel 29 to the cylinder 27. In the preferred embodiment, a rear extension 29b is formed integrally on the barrel 29 in a position proximate to the forward extension 27b of the cylinder 27 when the barrel and cylinder are attached.

So that the test barrel assembly 17 will, as closely as possible, recreate the firing conditions in an actual revolver, a gap of predetermined thickness is provided between the forward extension 27b of the cylinder 27 and the rear extension 29b of the barrel 29. This is accomplished by the use of a plurality of spacers 41 which may be in the form of tubular cylinders, one of which is placed over each cap screw in the space between the cylinder 27 and the enlarged attachment portion 29a of the barrel 29. To provide a gap of a particular thickness, spacers 41 of a particular length will be used. For example, if the space between the forward surface of the cylinder 27 and the rear surface of the enlarged attachment portion 290 of the barrel 29 is 0.250 in. without any gap between the extensions 27b and 2%, the use of a plurality of spacers, each having a length of 0.258 in., will produce a space between the extensions 27b and 29b of 0.008 in. Clearly, a change in the length of the spacers will result in a corresponding change in the thickness of the gap so that the venting of gases through the gap may be closely controlled and adjusted to any desired amount.

As will be readily apparent from the foregoing description, proper alignment between the barrel 29 and cylinder 27 is critical for proper functioning of the test barrel assembly 17. The chamber 30 in the cylinder 27 must be coaxial with, and bear a proper dimensional relationship to, the rifled bore 37 of the barrel 29; each of the passages 39 in the enlarged attachment portion 29a of the barrel 29 must be properly aligned and oriented with respect to the corresponding blind bores 34 in the cylinder 27; and the facing surfaces of the barrel and cylinder and of their extensions must maintain a parallel relationship to each other when the barrel and cylinder are attached by the cap screws 40 so that the spacers 41 may provide a uniform gap between the extensions 27b and 29b without disturbing the alignment of the chamber 30 with the rifled bore 37. It is also desirable that these precise dimensional relationships be provided without excessive machining costs.

To accomplish this, the cylinder 27 and barrel 29 are both machined from a single piece of metal. A blank 50 (see FIG. 5), preferably made of steel, is turned to have a barrel portion 50a, which is not less than the length desired for the finished barrel 29, and an enlarged portion 50b of sufficient length to be machined into the cylinder 27 and the enlarged attachment portion 29a of the barrel 29. An axial passage 51 is bored through the blank 50 and rifled and preferably has a diameter corresponding to the dimensions of the particular caliber bullet to be tested in the finished test barrel assembly. A groove 52 is then turned inv the enlarged portion 50b of the blank 50 forming a central portion 500 of reduced diameter. A plurality of openings are drilled in the enlarged portion 50b of the blank 50, bridging the groove 52 and forming the passages 39 and, when tapped, the blind bores 34. After separation of the barre] and cylinder, the blind bores 34 of the cylinder 27 and the passages 39 of the barrel 29 will, without further adjustment, be properly aligned. The central portion 50c is then cut so that the cylinder 27 and barrel 29 are formed. Further machining causes these parts to assume the form shown in FIG. 4, the rifling being removed from within the cylinder 27 when the chamber 30 is formed. A mandrel (not shown), dimensioned to fit tightly within the bore 37 and the chamber 30, is inserted through the cylinder and barrel so that they are placed in proper alignment for assembly. Insertion of the cap screws 40 with appropriate spacers 41 results in completion of a properly aligned test barrel assembly 17.

The assembled test barrel assembly 17, with the piston 32 removed, is inserted into the forward end of the body member 12 of the universal receiver 11 (see FIG. I), proper orientation being provided by interaction of the alignment notch 35 on the cylinder 27 with the alignment stud 36 of the universal receiver. A spacer 55 is positioned in the universal receiver forwardly of the test barrel assembly 17 and the lock nut 16 is threaded into the body member 12 to firmly secure the test barrel assembly 17 in place. The piston 32 may then be inserted between the wall portions 12a into the passage 31 and the pressure measuring device 26 clamped in place. The universal receiver 11 is thus prepared for operation as soon as a revolver cartridge to be tested is inserted into the chamber 30.

When a cartridge is fired in the universal receiver 11, gases are vented through the gap between the forward extension 27b of the cylinder 27 and the rear extension 29b of the barrel 29, thus simulating the gas venting action which occurs in an actual revolver. These vented gases pass through the space between the wall portions 120 of the body member 12 and thus encounter no back pressure which would result in erroneously high readings. Because the barrel 29 is made the same length as the gun for which ballistic readings are to be determined and the gap is made to conform to that of the gun type, meaningful pressure and velocity readings can be obtained for revolver ammunition. By changing the spacers 41 to increase the thickness of the gap, the venting of gases through the gap can be increased to simulate the effects on internal ballistics of excessive gun wear.

Significance of the use of the test barrel assembly 17 of this invention can be clearly demonstrated by a comparison of ballistic measurements. For example, in firing tests wherein velocities were measured in 6 in. barrels for 0.38 Special cartridges having lead bullets, the velocity measured for a cartridge with a 158 grain bullet, when fired in a standard unvented test barrel, of the type approved and used by the Sporting Arms and Ammunition Manufacturers Institute (SAAMI), was 875 ft./sec. When fired in a test barrel assembly made in accordance with this invention and having a gap between the cylinder and barrel of 0.008 in., the velocity was measured at 780 ft./sec. Thus, the measurement with the SAAMI unvented test barrel was about 12.2 percent higher than the velocity which would result from firing the cartridge in an actual revolver. In another test utilizing a 200 grain bullet, the unvented test barrel produced a velocity reading of 760 ft./sec. while the vented test barrel of this invention produced a reading of 675 ft./sec. In this case, the use of the unvented barrel resulted in a velocity reading which was 12.6 percent high. In other tests, velocities in excess of percent higher than the actual ballistic values have been found in standard prior art test barrels.

In a further test, velocity readings were taken in a vented test barrel in accordance with this invention with the gap set at 0.008 in. The gap was then increased to 0.020 in., representing an increase not uncommon in heavily fired revolvers, and further readings were taken. Cartridges which produced readings of 920 ft./sec. and 930 ft./sec. with the gap set at 0.008 in., were found to produce velocity readings of 822 ft./sec. and 784 ft./sec., respectively, when the gap was increased to 0.020 in. These figures represent velocity decreases of 10.6 percent and 15.7 percent, respectively.

We claim:

1. A method of manufacturing a test barrel assembly for testing a revolver cartridge from a metal blank, said method comprising the steps of forming a longitudinal passage through the metal blank, cutting the blank to form a barrel portion and a cylinder portion each including a section of the longitudinal passage, attaching the barrel portion to the cylinder portion with the sections of the longitudinal passage in axial alignment and with a gap of predetermined thickness between the barrel portion and the cylinder portion.

2. A method as in claim 1 wherein attaching the barrel portion to the cylinder portion includes the steps of positioning the barrel portion and cylinder portion with the sections of said longitudinal passage in axial alignment, positioning spacer means between the cylinder portion and the barrel portion, and securing the cylinder portion to the barrel portion with the spacer means held tightly between said portions.

3. A method as in claim 2 wherein a plurality of aligned pairs of attachment openings are drilled in the barrel portion and the cylinder portion before said blank is cut, and the barrel portion and cylinder portion are secured by threaded fasteners in each of the aligned pairs of attachment openings.

4. A method as in claim 3 wherein said threaded fasteners are passed through openings in said spacer means when securing the barrel portion to the cylinder portion.

5. A method of manufacturing, from a cylindrical metal blank having a thick portion and a thin portion, apparatus for testing a revolver cartridge, said method comprising the steps of forming a longitudinal rifled passage through the metal blank, cutting a radial groove in the thick portion of the blank to form a cylinder portion, a barrel portion and a central portion, drilling a plurality of longitudinal attachment openings, each extending into the barrel portion and the cylinder portion, cutting through the central portion to separate the barrel portion from the cylinder portion, forming a chamber in the cylinder portion, positioning a mandrel in the longitudinal passage in the cylinder portion and the barrel portion, positioning spacer means between t the cylinder portion and the barrel portion, and attaching the cylinder portion to the barrel portion with threaded attachment means in the longitudinal attachment openings.

Dedication 3,885,293.0ha4"les H. Bateman, J12, East Haven, Allan A. Campbell, Trumbull, and James J. Uapasso, Shelton, Conn. METHOD OF MAK- ING VENTED TEST BARREL ASSEMBLY FOR REVOLVER AMMUNITION. Patent dated May 27, 1975. Dedication filed July 28, 197 5, by the assignee, Remington Amms Company, I no. Hereby dedicates the remaining term of said patent to the Public.

[Ofiicz'al Gazette Decembea' 16, 1.975.] 

1. A method of manufacturing a test barrel assembly for testing a revolver cartridge from a metal blank, said method comprising the steps of forming a longitudinal passage through the metal blank, cutting the blank to form a barrel portion and a cylinder portion each including a section of the longitudinal passage, attaching the barrel portion to the cylinder portion with the sections of the longitudinal passage in axial alignment and with a gap of predetermined thickness between the barrel portion and the cylinder portion.
 2. A method as in claim 1 wherein attaching the barrel portion to the cylinder portion includes the steps of positioning the barrel portion and cylinder portion with the sections of said longitudinal passage in axial alignment, positioning spacer means between the cylinder portion and the barrel portion, and securing the cylindEr portion to the barrel portion with the spacer means held tightly between said portions.
 3. A method as in claim 2 wherein a plurality of aligned pairs of attachment openings are drilled in the barrel portion and the cylinder portion before said blank is cut, and the barrel portion and cylinder portion are secured by threaded fasteners in each of the aligned pairs of attachment openings.
 4. A method as in claim 3 wherein said threaded fasteners are passed through openings in said spacer means when securing the barrel portion to the cylinder portion.
 5. A method of manufacturing, from a cylindrical metal blank having a thick portion and a thin portion, apparatus for testing a revolver cartridge, said method comprising the steps of forming a longitudinal rifled passage through the metal blank, cutting a radial groove in the thick portion of the blank to form a cylinder portion, a barrel portion and a central portion, drilling a plurality of longitudinal attachment openings, each extending into the barrel portion and the cylinder portion, cutting through the central portion to separate the barrel portion from the cylinder portion, forming a chamber in the cylinder portion, positioning a mandrel in the longitudinal passage in the cylinder portion and the barrel portion, positioning spacer means between the cylinder portion and the barrel portion, and attaching the cylinder portion to the barrel portion with threaded attachment means in the longitudinal attachment openings. 